The Potential of High‐throughput Metagenomic Sequencing of Aquatic Bacterial Communities to Estimate the Postmortem Submersion Interval

Abstract

Human remains can be discovered in freshwater or marine ecosystems, circumstances where insects and other invertebrates have infrequently been used for understanding the time of postmortem submersion. In this study, the identification and succession of epinecrotic bacterial communities on vertebrate remains were described during decomposition in a temperate headwater stream during two seasons (summer and winter). Bacterial communities were characterized with 454 pyrosequencing and analyzed at phyletic and generic taxonomic resolutions. There was a significant increase in genera richness over decomposition during both seasons. Additionally, multivariate statistical modeling revealed significant differences in bacterial communities between seasons at both taxonomic resolutions and siginificant genera differences among sampling days within each season, suggesting a succession of these communities. These data are the first to describe aquatic bacterial succession using high-throughput metagenomic sequencing on vertebrate remains submerged in a freshwater habitat, and provide initial evidence for their potential use in forensic investigations.

Potential Using of Molecular Characterization and Structure of The Gut Bacterial Community for Postmortem Interval Estimation in Sprague Dawley Rats

“…Although the dominant bacterial community diversity at the phyla level showed no evident uctuation, we found that changes in the phyla Firmicutes and Proteobacteria were in the opposite direction of the relative abundance over time, which was consistent with a previous study [27]. Previous research aiming at the epinecrotic communities on human corpses showed that Firmicutes formed the inherent phylum for corpses, while Proteobacteria was initially identi ed from the environment, and the reason for the increase in Proteobacteria was outer bacterial migration [28][29][30]. This suggests that the increased relative abundance of Proteobacteria in the rectum of dead rats after 8 h may be due to the migration from the external environment.…”

Estimating the postmortem interval using microbes: Knowledge gaps and a path to technology adoption

“…Similar to vertebrate decomposition in terrestrial systems (e.g [12]. ), early decomposer communities were dominated by bacteria in the phylum Proteobacteria and later decomposer communities were dominated by bacteria in the phylum Firmicutes [34]. Postmortem taxa appeared to be a mix of mammal-associated and water-associated organisms [34].…”

“…Another major knowledge gap is how different environments such as terrestrial, aquatic, and indoor/built environments affect the succession of microbes during mammalian decomposition. In a study of swine decomposition in freshwater, Benbow et al [34] discovered a similar succession of microbes across individuals in two seasons. Similar to vertebrate decomposition in terrestrial systems (e.g [12].…”

Barnacle colonization of shoes: Evaluation of a novel approach to estimate the time spent in water of human remains

“…The typical decomposition process in aquatic environments may be affected by both environmental factors and factors related to the body itself. Environmental factors include, but are not limited to, water temperature, salinity, water depth, current flow, the season of submergence, availability of the body to macro and micro scavengers, water chemistry, and aquatic microbiome (4,(11)(12)(13)(18)(19)(20).…”